Liquid level indicator



March 2,1937.. R. c. scoTT '2,072,223 v LIQUID LEVEL INDICATOR 4Filed oct. 15, 1931 Patented Mar. 2, 1937 UNITED STATE LIQUID LEVEL IimIcAtroRl o Robert c. sem, cambridge, Mass. lApplicationOctober l15, 1931, Serial No. .569,010 i i y (ci. 177-351) 3 Claims.

f onewhich may advantageously'form a cooperative part of such a mechanism in an exemplary and, specifically advantageous embodiment.

My invention will be ywell understood'by reference to the` following'description ofthe specific embodiment thereofshown by wayofvexamplev in the accompanying drawing, wherein:--y o Fig.,l `is `a. view partly vin side elevation-and partlyvin sectionof a water column'and associated parts with parts broken away and 'electrical mechanism diagrammatically shown;` and *o Fig. 2 is arsection through alpreferred form of core utilized in the construction. t

Referring to the drawing, I have there shown a so-called water column 3 of known form, herein consisting of a cast steel receptacle closed by the cap 5 at the top and having steam and water inlets 9 adapted to be attached to the boilerin the usual manner. I have herein shown as associated with the column an inclined gage glass II of a type commonly used therewith and embodying the principles of the patent to Lank 1,307,892, June 24, 1919, but the presence or absence of such a glass is not material and it forms no part of my present invention. Atthe bottom ofthe isindicated. exteriorly of thel column by suitable means, preferably of thekiridy hereinafter described.r In the preferredfcrnfil illustrated, this mechanism embodies cooperating displacementv members I1 and I9 preferablyin the form of solid masses of non-corrodingfmaterial normally partly submerged 4in the water, and mutually counterpoising one another. o, I -Ierein member I'I is centrally disposed and surroundedby I9 which is of annular form land.the-central member is attached to a cross-,bar 2 I suspended by links `23 to theends of levers 25 Divoted on bearings carried` by thecap 5,.the opposite ends of the levers being connected by links 21 `to the exterior member I9, these providing a symmetrical suspension for the latter. The members thus mutually counterpoisedand centered in the column oat in the water and their buoyancies act in opposite direction to produce a'diierent'ial resultant movement when the Water level changes.V As `the height of water inthe column increaseseach of the bodies will be given an upward force equal to the weight of water it displaces.' Since the outer annular member I9 has a greater effective volume than'the` inner member I1, the upward f o'rce' on theiifouter section *willbe greater than the upwar'cl force on the inner sectionso that the outer"'section '-will' move upward and vlthe' inner section, downward'until 'the upward forces upon both -sections areequal and the' weight of. water displaced byfboth sectionsisequal. It will be noted that the amount of motion is the same irrespectiveof the specic gravity of the water or other liquid which might be in question. The resultant motion is preferably in reduced ratio to 'the variation in theheight of the water, and by varying the crosssection of'one or both of ,the

parts `II or I9 as-,indicated in the drawing-the proportion may'be changed as desired and may vary within therange of the mechanism. 4

The mechanism just described constitutes an example of a counterpoised displacement means particularly advantageous for use with electric signalling mechanism such as I am about to describe. y

Herein the column 3 is provided with an extension 29 preferably taking the form as shown of a depending coaxial leg. `'Ihis leg forms a dead rend which, however, may be provided with a drain tap 3|. The upper end may extend into the column as indicated at 33" and carry a support 35 on which the outer member I9 may rest in its lowermost position. Such. an extension 33 also denes a trap-like space 3'I'in which sediment may settle to be withdrawn through pipe I3 and it will notpass to the ,interior of the depending leg 29. 1. i

vT he member vII in the arrangement,l described is centered directly over the leg. Directly-suspended within the .leg 29 from the member I'I, v

as by means rof a corrosion-resisting rod or chain v39, is a member-4I, which I will refer toy asl-a coreand `which consists essentially of a body of material of` high magnetic permeability. Preferably it, may be constructed asshown in Fig. 2 of laminations 43 ,of -soft iron tightly enclosed within la, protective` casing of corrosion-resisting, high resistance material, such as nickel-chrommm-alloy.` IN'I'he core V4I`in its movement'responsiveto the movement of the "iloat mecha- -v i nism operates within a. casing 41 of high resistance material forming a part or extension of the depending leg 29.

The movement of the core 4| within the casing 41 is manifested exteriorly at any suitable remote point by means of a suitable instrument 49, herein shown asrof the indicating type, by electromagnetic means preferably of the impedance bridge type, a preferred form of which I will now describe. Surrounding the casing 41 I provide suitable coils 5i and 53 made of insulated wire, conveniently wound upon insulating spools held in position about casing 41 by means of the nuts 55. Cooperating with these coils are coils Bia and 53a as a part of instrument 49 with which coils in the embodiment of the invention illus'- trated cooperate respectively the soft iron cores 51 and 59 connected to the ends of a rocker arm 6i, the movements of which may operate a suitable pointer 53 as, for example, by means of the segment and pinion drive shown.

The coils 5I and 53 are connected vin series to a suitable source of alternating current 55 by means of theconductors 51, 89, 1I and 13 while the coils 5|a and 53a are similarly connected in series by the conductors 51, 15, 11 and 19. 'Ihe conductors 1I and 11 which connect the pairs of coils respectively are themselves connected by conductor 3|. By this arrangement coils 5| and 5Ia are connected in'parallel between 31 and 1I and coils 53Y and 53a between 3| and 19. Coils 5i and 53 are preferably so wound that whencurrent is flowing from 55 to 13 the magnetic polarity of the adjacent ends of the coils will be opposite and likewise that of the relatively remote ends, but such construction is not essential. Likewise the coils 5 la and 53a are preferably so wound that if current is flowing in 15 to 19, the magnetic polarity of the upper ends will be opposite and likewise that of the lower ends although this direction of magnetic polarity is not of importance in a construction like that illustrated in which the coresv 51 andi! of the two coils are individual and separate and not connected by magnetic material.

In the construction shown when the core 4| moves downward in response to an increase of water in the boiler, the inductance of coil 53 is increased due to a decrease in theumagnetic reluctance and consequently the impedance to the flow of current is increased. y

Also, the inductance of the Vcoil 5l is decreased due to an increase in the magnetic reluctance and consequently the impedance to the flow of current is decreased. 'Ihis results in the decrease in current now through the coils 53 and 5in and. an increase in current flow'through the coils 5I and 53a. The increase in current ow in coll 5I relative to the current now-in coil 53 will unbalance the magnetic flow between the cores 51 and 55 and their respective coils and move 59 downward until the magnetic forces between core 59 and coil 53a are equal to the magnetic forces between Athe core 51 and the coil 5in, and this movement of the cores 51 and 59 will operate pointer 53 and thus indicate movement of core 4I and the level of the water in the column 3. A condition of equilibrium is established when the ratio of inductances of the coils 53a, and Bia becomes. equal to the ratio between the inductances of the coils 5I and 53 and the impedance bridge is thereby rebalanced. Similarly, on any other movement of the core 41 there is a corresponding proportional movement of the cores 51 and 59 so that for an upward movement of the core 41 core 5I will move downward and core 51 upward, and

Ithe same.

for a downward movement of the core 41 core 53 will move upward and core 51 downward.

It will be noted that the displacement mechanism and thecore 4I operated thereby are all completely enclosed and that the electric mechanism is completely exterior to such enclosure with obvious advantages. By the use of counterpoised displacement means, as exempliiied by the diiferential mechanism shown, a direct suspension of the core v4I is permitted. The core thus may be made-as large and heavy as necessary since its weight is itself counterpoised and adequate buoyancy may be provided for operating 'I'he construction also permits the core to be operated in a dead-ended leg as shown and conveniently with the arrangement described to trap out sediment in the space 31. The electric transmitting mechanism comprising the coils 5I and 53 may thus be positioned at a suitable distance from the water column so that it is not exposed to deleterious temperatures, say 60 C. or more. To further aid in dissipating heat and to minimize the spacing between the electric mechanism and the water column, the leg 29 between casing 41 and the water column 3 may be provided with heat-dissipating ilns 33. When a diiferential displacement mechanism as herein described is used, the movement of core 4I may be within a suitable range independent of the axially greater range of uctuation of water level in the column 3.

I am aware that the invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and I therefore desire the present embodiment to be considered in all respects as illustrative and not restrictive; reference being had to the appended claims rather than to the foregoing description to indicate the scope of the invention.

I claim: 1

1. A water level indicating device comprising a water column for'connection witha boiler or the like, wherein the water level is subject to a considerable range of fluctuation, having a leg depending from the bottom thereof to provide a dead end, a displacement member received in said column to operate in line with said leg, counteracting displacement means cooperating with said member to producin said member a resultant diierenti'al movement proportional in reduced ratio to changes of liquid level in the column, a core of magnetizable materialin said depending leg, connected to said displacement members to be moved at the reduced ratio, and means including a remote indicator for exhibiting the position of said core, comprising an impedance balance having a pair of coils exterior to the depending leg at the location of the core, whereby the movement of the core is' substantially'less than that of the water level and is within the effective range of the adjacent coils of the impedance balance.

2. A liquid level indicating device comprising a liquid column for connection with a boiler orl the like, wherein the liquid level is subject to a considerable range of fluctuation, having a leg depending from the bottom thereof to provide a dead end, a displacement member received in said column to operate in line with said leg. a core of magnetizable material in said leg, meams connecting said displacement member to said jcore including differential means for producing in said core a resultant movement proportional in reduced ratio to changes of liquid level in said column, and means including a remote indicator for exhibiting the position of said core, comprising an impedance balance having a pair of coils exterior to the depending leg at the location of the core, whereby the movement of the core is substantially less than that of the liquid level and is within the eiective range of the adjacent coils of the impedance balance.

3. A liquid level indicating device comprising a liquid column for connection with a boiler or the like, wherein the liquid level is subject to a considerable range of uctuations, having a leg depending from the bottoml thereof to provide a dead end, a displacement member received in said column to operate in line with said leg, counteracting displacement means cooperating with said member to produce in said member a resultant differential movement proportion in reduced ratio to changes of liquid level in the column, the proportionality varying for increment changes of liquid level in the column, a core of magnetizable material in said depending leg, connected to said displacement members to be moved at the reduced ratio, and means including a remote indicator for exhibiting the position of said core; comprising an impedance balance having a pair of coils exterior to the depending leg at the location of the core, whereby the movement of the core is substantially less than that of the liquid level and is Within the eiective range of. the adjacent coils of the balance.

ROBERT C. SC.

impedance 

